Display devices using liquid crystals are widely used for portable devices, computers, wide-screen televisions, and the like because they are lighter in weight, are thinner, and consume less electric power as compared to conventional display devices such as a cathode ray tube. Liquid crystals do not emit light by themselves. Therefore, a backlight unit may be used for emitting light from behind liquid crystals to display a screen on a display device. Generally, a backlight unit includes a backlight assembly having a light-emitting element substrate including light-emitting elements such as light-emitting diodes (LEDs), a power supply substrate for supplying electric power and control signals to the light-emitting elements, and an electric conduction path connecting the light-emitting element substrate and the power supply substrate to each other.
For example, there has been known a backlight assembly having a structure including a chassis, a light-emitting element substrate fixed on a front face of the chassis, a power supply substrate fixed on a rear face of the chassis, and a harness passed through a hole formed in the chassis. The harness is used as an electric conduction path electrically connecting the light-emitting element substrate and the power supply substrate. See JP-A 2009-295587 (Patent Document 1). In the backlight assembly having such a structure, the hole of the chassis should be closed such that dust such as fine particles does not enter the backlight unit.
Next, an example of a backlight assembly having a structure that is different from but similar to the structure disclosed in Patent Document 1 will be described with reference to FIGS. 31 to 33.
As shown in FIGS. 31 and 32A to 32C, the backlight assembly has a chassis 103 having a frame 103b formed on a periphery of a front face of the chassis 103. The backlight assembly includes light-emitting element substrates 123a-123f screwed on the frame 103b. In FIGS. 32A to 32C, the light-emitting element substrates 123d, 123e, and 123f are omitted from the illustration. Each of the light-emitting element substrates 123a-123f includes light-emitting elements 131, such as LEDs, and a light-emitting element connector 133.
Meanwhile, as shown in FIG. 33, the backlight assembly has a power supply substrate 237 screwed on a rear face of the chassis 103. The power supply substrate 237 supplies electric power and control signals to the light-emitting element substrates 123a-123f. The power supply substrate 237 has power supply substrate connectors 235 mounted thereon.
The light-emitting element substrates 123a-123f and the power supply substrate 237 are electrically connected to each other via a harness 233. Specifically, the harness 233 has light-emitting element connectors 143 formed on one side of the harness 233 and power supply substrate connectors (not shown) formed on the other side of the harness 233. The light-emitting element connectors 143 are connected to the light-emitting element connectors 133. The power supply substrate connectors are connected to the power supply substrate connectors 235.
The chassis 103 has a hole 234 formed therein for allowing the harness 233 to pass therethrough. The hole 234 is filled with a rubber plug 231. The rubber plug 231 has small holes 231a like slits for allowing the harness 233 to pass therethrough.
In order to assemble such a backlight assembly, the following steps are required:
1) The light-emitting element substrates 123a-123f are attached to the chassis 103.
2) The light-emitting element connectors 143 of the harness 233 are connected to the light-emitting element connectors 133 of the light-emitting element substrates 123a-123f. Then the harness 233 is drawn out of the hole 234 toward the rear face of the chassis 103.
3) The hole 234 is filled with the rubber plug 231.
4) The power supply substrate 237 is fixed to the rear face of the chassis 103.
5) The power supply substrate connectors 235 of the power supply substrate 237 are connected to the power supply substrate connectors of the harness 233.